police say adam lanza used several 30-round clips on a semi-automatic rifle to shoot the 26 victims at sandy hook elementary. >> these mass killings have to stop and we have do everything we can. it will include looking at how many bullets do you need in a magazine in a semi-automatic weapon. >> on "meet the press," david gregory asked the nra's chief spokesman, why not bring back the ten-year ban that expired in 2004. >> i don't believe that's going to make one difference. there are so many different ways to evade that. you had that for ten years. it was on the books. columbine occurred right in the middle of it. it didn't make any difference. >> the prospect of a ban on magazines or the kind of guns called assault weapons have people in atlanta standing in line for more than an hour at a gun show. customers at this shooting ranging in arizona say those weapons are widely used by sportsmen. >> guys that shoot clays, guys that shoot trophy animals, you know, a lot of them are done with semi-automatic hunting rifles. >> a group representing mothers says it will fight hard for a ban. >> 80 mil